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Giant Toilet

June 6, 2016

In the summer of 2015 a class of Drexel Architecture and Design students worked with Greensgrow to create and develop a plan for its new site at 51st and Baltimore Avenue. Working collaboratively, the students generated several iterations of a balanced program that accommodates many uses, including the facilities for a Solar Composting Toilet. Architecture student Matthew Wang generated the final construction documents for the Solar Compost Toilet with advice and guidance from Jason Austin, Architecture Professor, who is also associated with the Greensgrow summer class and the independent study advisor for Matt's project. The Solar Composting Toilet is a unique approach to composting in an effort towards sustainable practices, to “close the loop” on the food/waste cycle by producing a nutrient rich compost product. The primary benefits of a solar compost toilet compared to a traditional commode are cleaner waste water and a fundamentally useful product. At Greensgrow, it will introduce and educate visitors to the sustainable concept that waste equals food. 

The compost toilet works first by separating liquids from solids.  The solids are collected in a bucket containing a mixture of sawdust and other natural material to dissipate remaining excess moisture.  The container of solids is then covered with a transparent lid and placed in direct sunlight for a period of several months allowing controlled decomposition to bake and cure the nutrients of harmful bacteria.  Earth and other soil mixtures can then be added to create the final nutrient rich compost product, which is only intended for use with ornamental plants and flowers that will not be used for human-consumption. The maintence of the composting process was made safe and convenient for Greensgrow employees by incorporating a beam with a hoist for lifting buckets to roof level.  After pulling a bucket from under the toilet it is capped and hooked to the hoist –rope is then tied to a cleat.  The employee then climbs a fixed ladder to the roof where the bucket can be detached and placed for baking.

Drexel’s Westphal College of Media Arts and Design has provided administrative support and use of their product design lab for Matthew to build the pieces of the compost toilet structure.  Upon completion of the pre-fabricated pieces they will be delivered to 51st and Baltimore where final assembly will take place.  Additional support for the project is provided by donation of waste building materials from Southeastern Pennsylvania Transportation Authority (SEPTA).  Labor is donated by building trades members of Transportation Workers Union Local 234. information about Greensgrow can be found at their website: